Many telecommunications switching systems might include plurality of I/O Cards, also known as network interface cards or line cards for processing different data from network interfaces like E1, DS1, STM-n, OC-n etc and send this processed data to traffic switch (also referred to as Switch card) to switch data from one network interface to other. In such telecommunication systems, the data from line cards to switch card passes over a backplane which connects various cards in a system. Such telecommunication system is called network element. The network interface cards also extract various overhead data from the interfaces and pass this overhead to overhead switch to switch across various other interfaces and to the processor for further processing.
In order to avoid single point of failure, it is well know method in the telecommunication systems to replicate critical sub systems like power supply, switch card, network element controller, system synchronizer etc. Such sub systems are called redundant sub systems, one acting as master and one or more acting as slave sub systems. Further, the critical subsystems like traffic switch, system synchronizer and chassis controller are integrated into single a card called controller. Such cards are replicated, one controller acting as master and one or more acting as slave controllers.
In network elements, where the line cards do not contain processor sub systems having processor and associated memory, various control and status signals are passed from each of the line cards to each of the controller cards and vice versa.
Consider an exemplary embodiment of conventional system, where there are two controller cards, 12 interface cards and 20 status or control signals running between each of the line card to each of the controller card. This makes 40 pins requirement at line card backplane interface and 240 pins requirement at controller card backplane interface. The increase in number of pins on the line card backplane interface and the controller card backplane interface will increase the routing complexity of backplane and complexity of PCB of the backplane. More over the requirement of 240 pins at controller backplane interface makes controller card designs complex and the controller card may not be able to accommodate so many connector pins along with traffic connectors. Also, the package size of the system is increased, which adds to the cost of implementing the telecommunications network. Further, future expansion of the system to include some more status or control signals is unmanageable.
FIG. 1 illustrates another embodiment of a conventional system illustrating a block diagram of devices connected to a backplane. Each of the devices of the first and second devices is connected to the backplane using a backplane connector. The devices can be either of a network interface card or a controller. The network interface card sends one or more signals to the controllers. These signals are sent using a separate pin for each of the signal. As a result, the numbers of pins on the network interface card, the controller and the backplane increases leading to increase of size of the backplane. Also, the cost of implementing such a system increases as managing such large number of pins on the backplane becomes difficult.
Therefore, there is a need to develop system architecture and a method to achieve effective communication between devices on a backplane by reducing number of pins on the backplane.